Mail problems

Greetings I have a concern my son writes regularly and it is very gratifying to receive news of his progress and his experiences but I have sent him almost a dozen letters and in which he arrived this week he tells me that he has only received two, I suppose the first and The address is fine because he has received at least two, now my questions are the following, that is normal and from now on with the situation that exists of the disease that is around, they will not delay the mail anymore.